Numerical studies of the electromagnetic Weibel instability in intense charged particle beams with large temperature anisotropy using the nonlinear best Darwin δf code

A numerical scheme for the electromagnetic particle simulation of high-intensity charged particle beams has been developed which is a modification of the Darwin model. The Darwin model neglects the transverse induction current in Amperes law and therefore eliminates fast electromagnetic (light) waves from the simulations. The model has been incorporated into the nonlinear deltaf Beam Equilibrium Stability and Transport(BEST) code. We have applied the model to simulate the transverse electromagnetic Weibel instability in a single-species charged particle beam and the mechanism for nonlinear saturation is identified.